New to knapping, help woth rock ID?

[Ippus]

Hey, y'all. I recently finished my first bow, and I'm starting on arrows. Eventually, the goal is to knap my own hunting broadheads, but for now I'm still at the trying-to-identify-knappable-rocks stage. Any tips on how to do that in SE Idaho would be appreciated. The geology around here seems to be a sort of random combination of limestone and volcanic.

I picked this rock up on a trail run earlier today. Based on the few youtube videos I've seen, it looked likely. Any idea what it is, or if I'm on the right track?

[Dakota Kid]

Looks pretty grainy to me. When I was a newb, I started with man made glass. It's free and plentiful, and more especially it knaps beautifully. Find an old school TV someone wants to get rid of. The picture tube glass is nearly an inch thick and works great. I'd watch a youtube video on how to safely remove it. They are under vacuum and can implode if you don't first slowly even out the pressure.

[Orrum]

Yes start with man made glass. For a year my girlfriend wold see me get my knapping stuff out and ask.....what are you breaking this time!#!   Now after 2 years I can make tomahawks really good with little breakage. Arrowheads fairly good but still break some, notching is tricky still. Blads I break about half and make them into neck knices or points. But rember I am doing percussion primarily. So just get some tools and start, it's amazingly satisfying to me even if I break something! Remember if you ain't bleeding you ain't knapping! LOL. It's a blood sport!

[Chippintuff]

That rock looks tough enough to be a hammer stone. Where it breaks you want to see a smooth surface.

WA

[mullet]

Looks like "Leaveitright".

[Ippus]

Looks like "Leaveitright".

lol, thanks everyone!

I'll keep an eye out for glass sources. Never would have thought of using an old CRT screen, Dakota. Are they heavily concave/convex like the bottom of a bottle, or convex on both sides like a lens?

[Chippintuff]

TV screens are thick. Curve doesn't make much difference.

WA

[Ippus]

Well, what do you know? I asked on facebook if anybody had old tvs or crt monitors to get rid of, and now I have 3 of them in my basement, aiting to be disassembled!

[Ippus]

Fantastic idea, guys!

About 3 hours (and a few minor cuts) later, and I have about 26 lbs of nice thick glass, in large pieces. Should be enough for me to manage a few arrowheads...

[StumblyRhino]

Wow, this is a great idea.  I had no clue.  Off to Craigslist!

[Ippus]

They're not kidding about doing a little homework before you open one up.
My grandpa was a tv repairman, and he used to swear he knew guys who got killed messing around inside a tv without grounding out the capacitor first.
Also, there's the risk of implosion if you crack the vacuum wrong.
And not as much these days, but it's still possible to get some heavy metals and such in you from the phosphor coating... Want to wear a dust mask and gloves and wash that off before you start knapping.

[StumblyRhino]

Thanks for the heads-up. I've discharged and vented them before, just never dawned on me that there was all that glass for knapping practice.  You could load the truck full of free CRT TVs off Craigslist in an afternoon.  They're everywhere.  Not that I'm going to get that many.

[Dakota Kid]

 The glass is actually crystal (i.e. leaded), so estimating quantity through weight might be a little misleading when compared to normal glass. I still knap TV glass from time to time. I almost always snap my larger pieces in half. The impact wave travels through the stuff with practically zero resistance. I have better luck using antler for percussion flaking, weighted copper seems to do more damage. Good luck. The stuff is almost too fragile, for me anyway. It will definitely teach you to hit the right spot or suffer the consequences.

Keep your eyes open for old toilets. Some of them knap pretty well, some are way to grainy. Once I found what I suspect was a chunk of old counter top that was like white glass. The stuff was amazing. I have seen anything like it since. Actually some coffee mugs are made of a similar material, but those are a far cry from 3/4" thick chunks of counter.